1. Field of the Invention
This application relates to a lens array unit for use in an information processing apparatus such as an image forming apparatus or an image reader, and also relates to an optical head that includes the lens array unit. Additionally, the application relates to the information processing apparatus that includes the optical head.
2. Description of the Related Art
A rod lens array unit is well known as a conventional lens array unit. The rod lens array unit may be used in an electrophotographic image forming apparatus with an LED (Light-Emitting Diode) head in which LEDs are linearly arranged or in an image reader such as a scanner or a facsimile machine that reads an image on a document by using a light receiving unit in which light receiving elements are linearly arranged. An optical system including the rod lens array unit can form an erected equal magnification image of an object.
Another conventional lens array unit includes two lens array plates that are arranged parallel to form an erected equal magnification image of an object. Micro lenses are linearly arranged on each of the lens array plates. The lens array plate with the micro lenses can be made by plastic injection molding. Japanese Patent Laid-Open No. 2000-221445 discloses one such lens array unit.
In the aforementioned lens array unit, however, since the lens array plate is thin in the direction of the optical axis of the micro lens, the bending rigidity of the lens array plate in the same direction is low. This makes it difficult to fabricate the lens array plate with high accuracy. Therefore, the conventional lens array unit is unable to form an image of an object at a desired resolution.